How to use a pen or pencil as stylus on your Sony Xperia Z1 display

Sony's Xperia Z Ultra phablet allows you to write or doodle on its display, using a regular pen or a pencil as a stylus, if you don't have one handy. It's a pretty cool feature, especially considering that Sony's giant handset carries a 6.4" screen, so there's plenty of canvas to work on.

It turns out that the 5" display on the Xperia Z1 also supports that feature, but Sony hasn't enabled it out of the box, for some reason.

If you are the proud owner of Sony's 20 MP flagship, and want the ability to write directly on the display with a pencil or ...